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Post by Telemachus on Mar 6, 2020 9:13:04 GMT
No. A battery’s ability to absorb charge, other things being equal, is proportional to its capacity. The 120Ah battery could absorb twice the current of the 60Ah ones. But since the 60Ah ones are set up for 24v, you only need half the Ah to get the same Wh. So it would all pan out the same. So when batteries are used for propulsion, the utilisation of multiples of 12v is advantageous only in terms of output? I was under the impression that such a config also allowed for faster charging times (which now appears to be entirely a facet of the type of batt being used). Using a high voltage battery configuration does not help output for propulsion in terms of the actual battery. Where it does help a lot, is in power lost in associated wiring / switching etc. Power being volts times amps, for a given power if you have high voltage, you have fewer amps. And it is amps, in conjunction with circuit and motor resistance, that causes power to be dissipated/wasted.
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Post by Deleted on Mar 6, 2020 15:01:12 GMT
Thank you all for the input, particularly Nick. There's nothing like food for thought, and some misconceptions have been blown to bits - good. I guess its 'shut up and calculate' for a while.
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Post by kris on Mar 6, 2020 15:25:26 GMT
As I said, I think they only make sense financially if you live aboard or spend a lot of time on your boat. I’m waiting for a bit to make a lead up for mine, but when I start using them I’ll report back.
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Post by Deleted on Mar 6, 2020 16:11:02 GMT
As I said, I think they only make sense financially if you live aboard or spend a lot of time on your boat. I’m waiting for a bit to make a lead up for mine, but when I start using them I’ll report back. What I'm considering is admittedly a toy. It is possible to live on a boat in a very basic way but having leccy is a good thing. In the past you would have needed to run the engine a lot to 'have it all', and if I was cruising I probably wouldn't want to be constantly on the move. So my concept is to have the minimum to do the minimum (lights, fridge, laptop or tablet, phone). I'm hoping for a system that can do all that with the least time spent running engines specifically for power possible. Everything points to the need for a lithium battery to achieve it. There's a 100Ah lithium item widely advertised at around £500 which is a hell of a lot for one battery. The question is, is 100Ah enough? Its really all about how much power the cold beer machine will need. Charger plus battery plus fridge equals pile of cash. Maybe things will get cheaper. Maybe it would be better to view the battery as a sacrificial item. Maybe I should forget the fridge. ETA And back then the thing I wanted a lot besides a fridge was a vacuum cleaner. Also a blender (to make the Margaritas)
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Post by Telemachus on Mar 6, 2020 18:53:51 GMT
As I said, I think they only make sense financially if you live aboard or spend a lot of time on your boat. I’m waiting for a bit to make a lead up for mine, but when I start using them I’ll report back. What I'm considering is admittedly a toy. It is possible to live on a boat in a very basic way but having leccy is a good thing. In the past you would have needed to run the engine a lot to 'have it all', and if I was cruising I probably wouldn't want to be constantly on the move. So my concept is to have the minimum to do the minimum (lights, fridge, laptop or tablet, phone). I'm hoping for a system that can do all that with the least time spent running engines specifically for power possible. Everything points to the need for a lithium battery to achieve it. There's a 100Ah lithium item widely advertised at around £500 which is a hell of a lot for one battery. The question is, is 100Ah enough? Its really all about how much power the cold beer machine will need. Charger plus battery plus fridge equals pile of cash. Maybe things will get cheaper. Maybe it would be better to view the battery as a sacrificial item. Maybe I should forget the fridge. ETA And back then the thing I wanted a lot besides a fridge was a vacuum cleaner. Also a blender (to make the Margaritas) A fridge uses more than you might think, maybe 30 or 40 Ah per day. So that doesn't leave a lot of change out of 100Ah battery, bearing in mind the usable capacity is perhaps 70Ah unless you are very careful with your charge management. One problem with a single "12v" Li battery is that you can't access the individual cell voltages, to check and balance. Unless you get one of the fancy ones with a brain inside and a connector for a computer.
Vacuum cleaner needs a powerful inverter to start it, but we have a Dyson D6 rechargeable which obviously runs off its batteries and when being charged, takes its power from the boat fairly slowly. Dyson's are not cheap though! (although they are good).
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Post by Deleted on Mar 6, 2020 18:58:15 GMT
I take the view that beer shops have ready chilled beer and accessing them can be quite an interesting little trip out.
This is inland in moderately populated areas. So a fridge is technically not needed. In wilderness areas I suppose it might be useful or just not have beer but that is quite a shocking option to be fair.
I could quite easily run my day to day life on the boat with something like a 20ah lithium power pack which could be charged by the boat engine or plugged into mains when I a location with mains power. Not sure how bulky the chargers on these are though.
I don't carry any man bags or rucksacks so no option to lug around bulky stuff. It would need to be small and efficient.
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Post by Deleted on Mar 6, 2020 20:11:31 GMT
I take the view that beer shops have ready chilled beer and accessing them can be quite an interesting little trip out. This is inland in moderately populated areas. So a fridge is technically not needed. In wilderness areas I suppose it might be useful or just not have beer but that is quite a shocking option to be fair. I could quite easily run my day to day life on the boat with something like a 20ah lithium power pack which could be charged by the boat engine or plugged into mains when I a location with mains power. Not sure how bulky the chargers on these are though. I don't carry any man bags or rucksacks so no option to lug around bulky stuff. It would need to be small and efficient. Really? You don't need a fridge? You mean - you won't die if you don't have a fridge? Hey everyone - you don't need a fridge! Far out. Thanks for the input. FYI It's not all about beer. You need pies too.
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Post by JohnV on Mar 6, 2020 20:19:14 GMT
the cold beer store on the yoghurt pot is the bilge, the pie coolbox, as is the butter/milk/cheese store is a different part of the bilge. Works for me (and pubs with beer and pies are quite frequent on the ditches
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Post by Telemachus on Mar 6, 2020 20:29:56 GMT
It’s not about the beer (which should of course be served at cellar temperature, not at fridge temperature). It’s about the ice (for G&T) and the chilled champagne.
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Post by JohnV on Mar 6, 2020 20:36:34 GMT
sorry, no ice ..... beer, cider and wine licence only
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Post by Deleted on Mar 6, 2020 20:52:21 GMT
What I'm considering is admittedly a toy. It is possible to live on a boat in a very basic way but having leccy is a good thing. In the past you would have needed to run the engine a lot to 'have it all', and if I was cruising I probably wouldn't want to be constantly on the move. So my concept is to have the minimum to do the minimum (lights, fridge, laptop or tablet, phone). I'm hoping for a system that can do all that with the least time spent running engines specifically for power possible. Everything points to the need for a lithium battery to achieve it. There's a 100Ah lithium item widely advertised at around £500 which is a hell of a lot for one battery. The question is, is 100Ah enough? Its really all about how much power the cold beer machine will need. Charger plus battery plus fridge equals pile of cash. Maybe things will get cheaper. Maybe it would be better to view the battery as a sacrificial item. Maybe I should forget the fridge. ETA And back then the thing I wanted a lot besides a fridge was a vacuum cleaner. Also a blender (to make the Margaritas) A fridge uses more than you might think, maybe 30 or 40 Ah per day. So that doesn't leave a lot of change out of 100Ah battery, bearing in mind the usable capacity is perhaps 70Ah unless you are very careful with your charge management. One problem with a single "12v" Li battery is that you can't access the individual cell voltages, to check and balance. Unless you get one of the fancy ones with a brain inside and a connector for a computer.
Vacuum cleaner needs a powerful inverter to start it, but we have a Dyson D6 rechargeable which obviously runs off its batteries and when being charged, takes its power from the boat fairly slowly. Dyson's are not cheap though! (although they are good).
Re the fridge of course you are right. The item touted as the most energy-efficient DC fridge available (and the least powerful in the range) would use a minimum of 40ah @ about 23°C and it of course rises with the ambient temperature. So it would seem advantageous to have the fridge linked to its very own solar panel as well as its own battery. This makes the entire system quite pricey, but it could perhaps manage with a 100ah battery like this. It occurred to me that the other things (led lights and i.t gadget life-support) don't need a Li battery as much, so perhaps a cheaper option to power such things might work. It would complicate the wiring a bit as well, I suppose. I once knew a girl who wanted a Dyson because they were expensive. Takes all sorts. I have used a 'Dust Devil' in the car for years. Works fine.
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Post by Deleted on Mar 6, 2020 21:00:17 GMT
the cold beer store on the yoghurt pot is the bilge, the pie coolbox, as is the butter/milk/cheese store is a different part of the bilge. Works for me (and pubs with beer and pies are quite frequent on the ditches What if the boat isn't a boat? Many moons ago I encountered an object that looked like a fridge but in fact had some kind of evaporation unit / heat exchanger. It required regular top-ups of water but had no moving parts and needed no power source of any sort (except the sun). You couldn't have called the inside cold exactly, but it kept milk fresh for longer.
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Post by Deleted on Mar 6, 2020 21:09:10 GMT
[Really? You don't need a fridge? You mean - you won't die if you don't have a fridge? Hey everyone - you don't need a fridge! Far out. Thanks for the input. FYI It's not all about beer. You need pies too. I never use a fridge on my boats. The woman uses a fridge all the time on her boat but when it's just me in my own boats it doesn't happen. Unnecessary extra equipment.
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Post by greenman on Mar 6, 2020 21:17:23 GMT
I take the view that beer shops have ready chilled beer and accessing them can be quite an interesting little trip out. This is inland in moderately populated areas. So a fridge is technically not needed. In wilderness areas I suppose it might be useful or just not have beer but that is quite a shocking option to be fair. I could quite easily run my day to day life on the boat with something like a 20ah lithium power pack which could be charged by the boat engine or plugged into mains when I a location with mains power. Not sure how bulky the chargers on these are though. I don't carry any man bags or rucksacks so no option to lug around bulky stuff. It would need to be small and efficient. Really? You don't need a fridge? You mean - you won't die if you don't have a fridge? Hey everyone - you don't need a fridge! Far out. Thanks for the input. FYI It's not all about beer. You need pies too. Why waste fridge space on pies, you can get pies in tins.
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Post by Deleted on Mar 6, 2020 21:17:59 GMT
[Really? You don't need a fridge? You mean - you won't die if you don't have a fridge? Hey everyone - you don't need a fridge! Far out. Thanks for the input. FYI It's not all about beer. You need pies too. I never use a fridge on my boats. The woman uses a fridge all the time on her boat but when it's just me in my own boats it doesn't happen. Unnecessary extra equipment. Yes, unnecessary, agreed. But desirable. Is the air-horn necessary?
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